Once-through type boiler



0. ENGLER Aug. 30, 1966 ONCE-THROUGH TYPE BOILER 2 Sheets-Sheet 1 FiledApril 22, 1965 FIG INVENTOR film; Z75 BY M3221! $5 ATTORNEY Aug. 1966 o.ENGLER 3,269,362

ONCE-THROUGH TYPE BOILER Filed April 22, 1965 2 Sheets-Sheet 2 INVENTORF/G. 2 0m 2;;

ATTORNEY United States Patent 12 Claims. (31. 122-435 The presentinvention relates to a once-through type boiler, that is to a boilerwithout steam drum in which the water is forced into a single circuit ofone or several tubes and steam is delivered at the other end.

Once-through type boilers are known in the art and it is also known toconstruct the furnace chamber of such a boiler, with which the burnermeans communicate, from helically formed tubes which contact each otheralong the length thereof and which are welded together along thecontacting portions thereof. In such a boiler, the water fed into thelower ends of the helically arranged tubes is heated up in the region ofthe lower end of the furnace chamber and the heated up water isgradually transformed into steam in an intermediate portion of the tubesforming the furnace chamber, while at the region of the upper endthereof the thus formed steam is super-heated. The volume of the mediumflowing through the tubes increases therefore from the lower to theupper end of the furnace chamber considerably. It would therefore bedesirable to increase the inner diameter of the tubes forming the upperportion of the furnace chamber, however this is not possible since largediameter tubes would not withstand the internal pressure they aresubjected to.

Furthermore, if the wall of the furnace chamber with which the burnermeans communicate is exclusively formed by the aforementioned helicallyarranged tubes, the heat absorption of these tubes becomes veryconsiderable so that a considerable difference between the tube portionsforming the lower part of the furnace chamber and the tube portionsforming the upper part of the furnace chamber will result, especiallysince the lower portions of the tubes are flown through by water fedinto the boiler, whereas the upper portions are flown through by hotsteam. While this difficulty can in part be overcome by sufiicient speedof the medium flowing through the tubes, experience has shown thatespecially in the upper portion of the furnace chamber overheating ofthe tubes will occasionally occur which may lead to a damage of thesame.-

It is an object of the present invention to overcome the aforementioneddifliculties encountered in once-through type boilers in which thecylindrical outer wall of the boiler is formed by helically wound tubesthrough which the fluid medium passes.

It is a further object of the present invention to limit the heatabsorption of the helically wound tubes forming the cylindrical wall ofthe boiler so as to reduce the difference between the heat expansion ofthe lower portions of the tubes and the upper portions thereof and toprevent overheating of the tubes in the region of the upper end of theboiler.

It is an additional object of the present invention to provide for aonce-through type boiler of the aforementioned kind which is relativelysimple in construction so that the boiler can be manufactured atreasonable cost and will stand up trouble-free under extended use.

With these objects in view, the once-through type boiler of the presentinvention mainly comprises an outer upright substantially cylindricalwall formed by a plurality of tubes extending substantially parallel incontact with each other in helical form from the lower to the upper endof the cylindrical wall and being welded to each other, a substantialvertical separating wall extending trans- 3,269,352 Patented August 30,1966 versely through the interior of the cylindrical wall and beingformed by a plurality of substantially vertical tubes welded togetherthrough a substantial portion of the length thereof so that the verticalwall divides the interior of the cylindrical wall into a furnace chamberand a heat exchange chamber. The aforementioned tubes of the verticalwall are arranged spaced from each other at an upper portion of the wallto provide communication between the furnace chamber and the heatexchange chamber at an upper portion of the separating wall. The boilerincludes further burner means communicating with the interior of thefurnace chamber, heat exchange means in the heat exchange chamber, andtubular means connecting the tubes of the cylindrical wall, the tubes ofthe separating wall and the heat exchange means to each other forpassage of fluid in a continuous pass therethrough.

It is to be understood that the term cylindrical wall as used in thespecification and the claims includes an outer wall of circularconfiguration as well as an outer wall of square or rectangularconfiguration having rounded corners.

The arrangement according to the present invention has the advantagethat each convolution of the substantially helically wound tubes formingthe outer boiler wall passes through zones at opposite sides of theseparating wall dividing the interior of the outer wall into the furnacechamber and the heat exchange chamber, that is through a greatly heatedzone and through a zone heated to a lesser extent, so that the heattransmitted to the tubes forming the outer wall of the boiler is reducedin comparison to known arrangements. The increase of the volume of themedium flowing through the helically arranged tubes is thereby reducedso that these tubes may be formed with uniform cross section.Furthermore, since the tubes forming the outer wall are arranged at arelative small angle inclined to the horizontal, a convolution passingat one side of the separating wall through a relative hot part of thefurnace chamber will pass at the other side of the separating wallthrough a relative cool part of the heat exchange chamber so thatadjacent tubes will be heated up to substantially the same extent and sothat the heat ex pansion of adjacent tube portions will be substantiallythe same.

The tubes forming the cylindrical wall as well as the tubes forming theseparating wall are preferably fin tubes arranged in such a manner thatthe free edges of the fins of adjacent tubes abut against each other andare welded to each other at the abutting edges.

Preferably, the boiler includes also annular reinforcing meanssurrounding the cylindrical wall and operatively connected thereto forpreventing bulging thereof. Preferably the heat exchange means extendtransversely through the heat exchange chamber with opposite portions ofthe heat exchange means respectively facing part of the cylindrical walldefining the heat exchange chamher, and the separating wall, and theconstruction includes preferably further bracing means between saidopposite portions of the heat exchange means and the aforementioned partof the cylindrical wall at one hand and the separating wall at the otherhand so that the separating wall is also supported intermediate the endsthereof.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. 1 is a greatly simplified flow diagram of a once through typeboiler according to the present invention;

FIG. 2 is a longitudinal schematic cross section through the boiler ofthe present invention; and

FIGS. 3 and 4 are detailed constructions of the boiler, shown partly incross section and drawn to an enlarged scale.

FIG. 1 shows a greatly simplified schematic flow diagram of theonce-through type boiler according to the present invention in whichsome parts of the boiler are omitted for reasons of simplification. Asschematically shown in FIG. 1 feed water is fed by by a pump P indirection of the arrow A into the lower ends of helically arranged tubesH, only one is shown in FIG. 1, which are arranged in a manner as willbe described in further detail latter on to form a substantiallycylindrical outer wall of the boiler. The upper ends of the tubes H areconnected to a collector located at the lower end of the boiler withwhich a plurality of substantially vertically extending tubes Scommunicate at the lower ends thereof and the vertical tubes S arearranged in a manner as will be describe-d in further detail later on toform a separating wall dividing the interior of the cylindrical wallformed by the helically arranged tubes A into a furnace chamber shown atthe left side of FIG. 1 and in a heat exchange chamber at the rightside, as viewed in FIG. 1, of the transverse wall formed by the verticaltubes S. Burner means communicate with the lower region of the furnacechamber so that the flames and hot combustion gases developed by theburner means pass in upward direction as shown by the dotted arrows Bthrough the furnace chamber and the upper portion of the vertical wall Sis constructed to permit passage of the combustion gases through theupper region of the vertical wall so that the combustion gases pass indownward direction as indicated by the dotted arrows through the heatexchange chamber to pass from the lower ends thereof into a flue. Thefeed water fed into the lower portion of the tubes H is heated up in the.lower portion of the boiler and the heated up water is graduallytransformed into steam during the forced passage of the water throughthe helically wound tubes from the lower to the upper end of thecylindrical wall. Obviously, the portions of the helically wound tubes Hwhich are located at the right side, as viewed in FIG. 1, of theseparating wall S will be heated up to a lesser extent than the portionsof the helically wound tubes which are located at the left side of theseparating wall and therefore the total heat absorption of the helicaltubes forming the cylindrical wall of the boiler will be less than thanit would be in the absence of the separating wall. The differencebetween the terminal expansion of the tube portions of the helical tubesat the lower part of the cylindrical wall and the upper part thereof isthereby greatly reduced.

FIG. 2 shows the construction of the boiler of the present invention infurther detail. As can be seen from FIG. 2, the boiler of the presentinvention comprises an upright substantially cylindrical wall formed bya plurality of fin tubes 13 extending in helical form substantiallyparallel to each other from the lower to the upper end of thecylindrical wall. It is mentioned that the angle of inclination of thetubes 13, that is the angle the tubes include with the horizontal is inthe actual construction much smaller than shown in FIG. 2. The fin tubes13 have diametrically opposite fins 13 extending in longitudinaldirection of the tubes (FIG. 4) and arranged so that the free edges ofthe fins 13' of adjacent tubes 13 abut against each other and are Weldedtogether along the abutting free edges thereof. The lower ends of thehelically wound tubes 13 communicate with an annular inlet collector 12,whereas the upper ends of the tubes 13 communicate with an annularoutlet 14. The boiler of the present invention further comprises asubstantially vertical separating Wall extending transversely throughthe interior of the cylindrical wall and being formed by a plurality ofsubstantially vertical fin tubes 19 extending substantially parallel toeach other and each having diametrically opposite fins abutting againsteach other along the free edges thereof and welded together along theabutting edges in the same manner as the fins in the helically arrangedtubes 13 are welded together. The vertical wall formed by the fin tubes19 divides the interior of the outer wall formed by the helicallyarranged tubes 13 into a furnace chamber F, located at the left side ofthe vertical wall, as viewed in FIG. 2, and in a heat exchange chamber Hlocated to the right side of the vertical wall. The upper portions 21 ofsome of the vertical tubes 19 are located in the plane of the verticalwall formed by the tubes 19, whereas upper portions 22 of adjacent tubeswhich alternate with the upper tube portions 21 are bent out of theplane in which the separating wall is located so that the tube portions22 are spaced from the tube portions 21 providing thereby openingsthrough which the upper end of the furnace chamber F will communicatewith the heat exchange chamber H. The tubes 19 forming the verticalseparating wall communicate at the lower ends thereof with an inletcollector 18 and at the upper ends thereof with an outlet collector 20.

Heat exchange means are located in the heat exchange chamber H of theboiler. These heat exchange means comprise tubular economizer means 3located in the lower portion of the heat exchange chamber,pre-superheater means 25 located in an intermediate portion of the heatexchange chamber, and additional superheater means 31 located in theupper part of the heat exchange chamber. The aforementioned describedelements are connected together and are supplied with a fluid means inthe fol-lowing manner: a

A feed water pump P feeds water from a reservoir not shown in FIG. 2into the lower inlet end or inlet collector 2 communicating with thelower end of the tubular economizer 3 located in the lower portion ofthe heat exchange chamber. The upper end of the economizer 3communicates with an outlet collector 4 of the economizer and the outletcollector 4 is connected by a tube 5 to an inlet collector 6 located atthe bottom of the boiler. A plurality of tubes 7 extend transverselythrough the lower end of the furnace chamber F from the bottom inletcollector 6 to the bottom outlet collector 8 and the latter is connectedby tubes 9 to a header 10 located beneath the bottom of the furnacechamber and communicating through a plurality of tubes with the annularinlet collector means 12 for the spirally arranged tubes 13 forming thecylindrical wall of the boiler. A plurality of tubes 15 lead from theannular outlet collector 14 to an injection cooler 16 which in turn isconnected by tubes 17 to an inlet collector 18 With which the lower endsof the tubes 19 forming the separating wall communicate. The outletcollector 20' with which the upper ends of the tubes 19 communicate isconnected by a plurality of tubes 23 to an inlet collector 24 whichcommunicates with the lower end of the pre-superheater 25. An outletcollector 26 in communication with the upper end of thepre-superheater25 communicates through tubes 27 with an additional cooler 28 and thelatter communicates through a plurality of tubes 29 with an inletcollector 30 communieating with the lower end of the additionalsuperheater 31. The upper end of the additional superheater 31communicates with a plurality of tubes 32 which extend transverselythrough the upper end of the cylindrical wall and which lead to a finaloutlet collector 33. The transverse tubes 32 are not Welded together anda cover not shown in FIG. 2 extends over and closes the upper end of thecylindrical wall.

Burner means 35 pass through a lower portion of the cylindrical wallwhich faces the separating wall and the burner means 35 communicate withthe interior of the furnace chamber F. The specific construction of theburner means 35 and the manner in which the inlet ends of these burnermeans are passed through the cylindrical wall of the boiler does notform part of the present i114 vention and burner means using pulverizedcoal, as well as oil burners may be used in connection with the boilerof the present invention.

A plurality of annular reinforcing means spaced from each other in axialdirection of the outer wall formed by the tubes 13 are provided whichsurround the outer wall operatively connected thereto to prevent bulgingthereof. The annular reinforcing means include l-beams 36 having innerflanges 36 (FIG. 3) engaged at upper and lower edges thereof by claws 37formed on plates 38 which are at the inner longitudinal edges thereofWelded to longitudinal extended tie bars 39, extending in longitudinaldirection substantially through the whole length of the outer wallformed by the tubes 13 and abutting with the inner surface thereofagainst the outer surface of the tubes 13. The tie bars 39 are anchoredat the upper ends thereof to a supporting structure 40 surrounding theactual boiler. The tie bars 3% are preferably connected by links 41 toupright I-beams 45 forming part of the supporting structure of theboiler. Each of the links 41 preferably comprises, as shown in FIG. 4,two short bars 32, arranged spaced from each other and substantiallynormal to the tie bar 39 and welded to the latter and a similar bar 43arranged between the bars 42 and Welded to the upright I-beam 4-5. Theshort bars 32 are formed adjacent the free ends thereof with borestherethrough aligned along a common axis in which a pin 44 is pressfitted which passes through an elongated slot 43 in the bar 43. Thelinks 41 connect therefore the tie bar 39 to the upright I-beams 45pivolally about the axis of the pin 4 S and also movable through thelength of the slot 43 toward and away from the upright l-beam. A sheetmetal shell 46 is preferably held by spot welding or the like on theupright I-beams surrounding the outer wall of the boiler and lagging ofheat insulating material 47 is interposed between the sheet metal 46 andthe outer surface of the tubes 13 forming the boiler wall so that thelatter is properly heat insulated. The outer Wall of the boiler formedby the fin tubes 13, as well as the separating wail formed by the fintubes 19 is supported at the upper end thereof at 34 to the supportingstructure 49 in any convenient manner not forming part of the presentinvention. The separating Wall formed by the tubes 19 is preferably alsoconnected by links 41, similar to the links shown in FIG. 4, to thetubes of the economizer 3, the tubes of the pre superheater 25 and theadditional superheater 31 and the tubes of the aforementioned elementsare connected at the opposite ends preferably also by similar links 41to the outer wall of the boiler formed by the tubes 13.

The operation of the boiler above described will be obvious from thepreceding description. Feed water is fed by the pump P in the inletcollector 2 of the economizer 3. The speed with which the feed water isfed into the boiler is at full load approximately between 1.9 and 2.5meters per second. During operation of the burner means 35 the feedwater is preheated in the economizer 3 and passes then in the manner asdescribed above into the inlet collector E2 to flow from there in upwarddirection through the plurality of helically arranged tubes 13 formingthe outer wall of the boiler. In the lower portion of the boiler thewater is further heated to be in intermediate section of the outer wallgradually transformed into steam so that steam will collect in theoutlet collector 14 at the upper end of the outer boiler wall from wherethe steam passes into the inlet collector 18 at the bottom of theseparating wall to be further superheated during the passage through thetubes 1h and the superheated steam is then guided through thesuperheater 25 and the additional superheater 31 to pass through theoutlet collector 33 to a point of use.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofonce-through type boilers differing from the types described above.

While the invention has been illustrated and described 6 as embodied inonce-through type boiler having an outer wall formed by welded togetherhelically arranged fin tubes, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of tubesextending substantially par allel in contact with each other insubstantially helical form from the lower to the upper end of saidcylindrical wall and being welded to each other; a substantiallyvertical separating wall extending transversely through the interior ofsaid cylindrical wall and being formed by a plurality of substantiallyvertical tubes welded together through a substantial portion of thelength thereof, said vertical wall dividing the interior of saidcylindrical wall into a furnace chamber and a heat exchange chamber,said tubes of said vertical Wall being spaced at upper portions thereoffrom each other to provide communication between said furnace chamberand said heat exchange chamber at an upper portion of said. separatingwall; burner means communicating with the interior of said furnacechamber; heat exchange means in said heat exchange chamber; and tubularmeans connecting the tubes of said cylindrical wall, the tubes of saidseparating wall and said heat exchange means to each other for passageof fluid in a continuous path therethrough.

2. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; a substantially vertical separating Wallextending transversely through the interior of said cylindrical wall andbeing formed by a plurality of substantially vertical fin tubesextending substantially parallell to each other with the free edges ofthe fins of adjacent fin tubes abutting against and welded to each otherthrough a substantial portion of the length thereof, said vertical Walldividing the interior of said cylindrical wall into a furnace chamberand a heat exchange chamber, said tubes of said vertical wall beingspaced at upper portions thereof from each other to providecommunication between said furnace chamber and said heat exchangechamber at an upper portion of said separating wall; burner meanscommunicating with the interior of said furnace chamber; heat exchangemeans in said heat exchange chamber; and tubular means connecting thetubes of said cylindrical wall, the tubes of said separating Wall andsaid heat exchange means to each other for passage of fluid in acontinuous path therethrough.

3. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical Wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; a substantially ver* tical separating wallextending transversely through the interior of said cylindrical wall andbeing formed by a plurality of substantially vertical fin tubesextending substantially parallel to each other with the free edges ofthe fins of adjacent fin tubes abutting against and welded to each otherthrough a substantial portion of the length thereof, said vertical walldividing the interior of said cylindrical wall into a furnace chamberand a heat ex change chamber, said tubes of said vertical wall beingspaced at upper portions thereof from each other to providecommunication between said furnace chamber and said heat exchangechamber at an upper portion of said separating Wall; burner meanscommunicating with the interior of said furnace chamber and arranged topass through a portion of said cylyindrical wall facing said separatingwall; heat exchange means in said heat exchange chamber; and tubularmeans connecting the tubes of said cylindrical wall, the tubes of saidseparating wall and said heat exchange means to each other for passageof fluid in a continuous path therethrough.

4. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; a substantially vertical separating wallextending transversely through the interior of said cylindrical wall andbeing formed by a plurality of substantially vertical fin tubesextending substantially parallel to each other with the free edges ofthe fins of adjacent fin tubes abutting against and welded to each otherthrough a substantial portion of the length thereof, said vertical walldividing the interior of said cylindrical wall into a furnace chamberand a heat exchange chamber, said tubes of said vertical Wall beingspaced at upper portions thereof from each other to providecommunication between said furnace chamber and said heat exchangechamber at an upper portion of said separating wall; burner meanscommunicating with the interior of said furnace chamber; tubular heatexchange means extending transversely through said heat exchange chamberand facing with opposite portions thereof, respectively, part of saidcylindrical wall defining said exchange chamber and said separatingwall; bracing means connecting said opposite portions of said heatexchange means respectively to said part of said cylindrical wall andsaid separating wall; and tubular means connecting the tubes of saidcylindrical wall, the tubes of said separating wall and said heatexchange means to each other for passage of fluid in a continuous paththerethrough.

5. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; annular reinforcing means surrounding saidcylindrical wall and operatively connected thereto for preventingbulging thereof; a substantially vertical separating wall extendingtransversely through the interior of said cylindrical wall and beingformed by a plurality of substantially vertical fin tubes extendingsubstantially parallel to each other with the free edges of the fins ofadjacent fin tubes abutting against and welded to each other through asubstantial portion of the length thereof, said vertical wall dividingthe interior of said cylindrical wall into a furnace chamber and a heatexchange chamber, said tubes of said vertical wall being spaced at upperportions thereof from each other to provide communication between saidfurnace chamber and said heat exchange chamber at an upper portion ofsaid separating wall; burner means communicating with the interior ofsaid furnace chamber; heat exchange means in said heat exchange chamber;and tubular means connecting the tubes of said cylindrical wall, thetubes of said separating wall and said heat exchange means to each otherfor passage of fluid in a continuous path therethrough.

6. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; a plurality of annular reinforcing meansspaced from each other in axial direction of said cylindrical Wall andsurrounding the latter operatively connected thereto for preventingbulging thereof; a substantially vertical separating wall extendingtransversely through the interior of said cylindrical wall and beingformed by a plurality of substantially vertical fin tubes extendingsubstantially parallel to each other with the free edges of the fins ofadjacent fin tubes abutting against and welded to each other through asubstantial portion of the length thereof, said vertical wall dividingthe interior of said cylindrical wall into a furnace chamber and a heatexchange chamber, said tubes of said vertical wall being spaced at upperportions thereof from each other to provide communication between saidfurnace chamber and said heat exchange chamber at an upper portion ofsaid separating wall; burner means communicating with the interior ofsaid furnace chamber; heat exchange means in said heat exchange chamber;and tubular means connecting the tubes of said cylindrical wall, thetubes of said separating wall and said heat exchange means to each otherfor passage of fluid in a continuous path therethrough.

7. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting againstand welded to each other; a plurality of annular reinforcing meansspaced from each other in axial direction of said cylindrical wall andsurrounding the latter operatively connected thereto for preventingbulging thereof; a substantially vertical separating wall extendingtransversely through the interior of said cylindrical wall and beingformed by a plurality of substantially vertical fin tubes extendingsubstantially parallel to each other with the free edges of the fins ofadjacent fin tubes abutting against and welded to each other through asubstantial portion of the length thereof, said vertical wall dividingthe interior of said cylindrical Wall into a furnace chamber and a heatexchange chamber, said tubes of said vertical wall being spaced at upperportions thereof from each other to provide communication between saidfurnace chamber and said heat exchange chamber at an upper portion ofsaid separating Wall; burner means communicating with the interior ofsaid furnace chamber; tubular heat exchange means extending transverselythrough said heat exchange chamber and facing with opposite portionsthereof, respectively, part of said cylindrical wall defining saidexchange chamber and said separating wall; bracing means connecting saidopposite portions of said heat exchange means respectively to said partof said cylindrical wall and said separating wall; and tubular meansconnecting the tubes of said cylindrical wall, the tubes of saidseparating wall and said heat exchange means to each other for passageof fluid in a continuous path therethrough.

8. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical Wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to said upper end of said cylindrical wallwith the free edges of the fins of adjacent fin tubes abutting; asubstantially vertical separating wall extending transversely throughthe interior of said cylindrical wall and being formed by a plurality ofsubstantially vertical fin tubes extending substantially parallel toeach other with the free edges of the fins of adjacent fin tubesabutting against and welded to each other through a substantial portionof the length thereof, said vertical wall dividing the interior of saidcylindrical wall into a furnace chamber and a heat exchange chamber,said tubes of said vertical Wall being spaced at upper portions thereoffrom each other to provide communication between said furnace chamberand said heat exchange chamber at an upper portion of said separatingwall, the outermost of said fin tubes forming said separating wall beingat least in part welded to said helical tubes forming said cylindricalwall; burner means communicating with the interior of said furnacechamber; heat exchange means in said heat exchange chamber; and tubularmeans connecting the tubes of said cylindrical wall, the tubes of saidseparating wall and said heat exchange means to each other for passageof fluid in a continuous path therethrough.

9. A once-through type boiler comprising, in combination, an outerupright substantially cylindrical wall formed by a plurality of fintubes extending in substantially helical form substantially parallel toeach other from the lower to the upper end of said cylindrical wall withthe free edges of the fins of adjacent fin tubes abutting against andWelded to each other; annular inlet collector means for said cylindricalWall and communicating with the lower ends of said fin tubes formingsaid cylinderical wall; annular outlet collector means for saidcylindrical Wall and communicating with the upper ends of said fin tubesforming said cylindrical wall; a substantially vertical separating wallextending transversely through the interior of said cylindrical wall andbeing formed by a plurality of substantially vertical fin tubesextending substantially parallel to each other with the free edges ofthe fins of adjacent fin tubes abutting against and welded together fromthe lower ends of the vertical tubes through a substantial portion ofthe length thereof, said vertical wall dividing the interior of saidcylindrical Wall into a furnace chamber and a heat exchange chamber,said tubes of said vertical wall being spaced at upper portions thereoffrom each other to provide communication between said furnace chamberand said heat exchange chamber at an upper portion of said separatingwall; inlet collector means for said separating wall and communicatingwith the lower ends of said vertical fin tubes; outlet collector meansfor said separating wall and communicating with the upper ends of saidvertical fin tubes; tubular economizer means located in a lower portionof said heat exchange chamber and having a lower inlet end and an upperoutlet end; tubular means providing communication between said outletend of said economizer means and said annular inlet collector means ofsaid cylindrical wall; tubular means providing communication betweensaid annular outlet collector means of said cylindrical wall and saidinlet collector means of said separating wall; tubular superheater meansin an upper portion of said heat exchange chamber and having a lowerinlet end and an upper outlet end; tubular means providing communicationbetween said outlet collector means of said separating Wall and saidlower end of said superheater means; burner means communicating with theinterior of said furnace chamber and passing through a lower portion ofsaid cylindrical wall facing said separating wall; pump meanscommunicating with said inlet end of said economizer means for feedingwater into the latter; and support means for supporting said cylindricalwall and said separating wall in the region of the upper ends thereof.

10. A boiler as set forth in claim 9 and including heat laggingsurrounding said cylindrical Walls.

11. A boiler as set forth in claim 9 and including a plurality ofannular reinforcing means spaced from each other in axial direction ofsaid cylindrical wall and surrounding the latter operatively connectedthereto for preventing bulging thereof.

12. A boiler .as set forth in claim 9, wherein said tubular meansproviding communication between said outlet end of said economizer meansand aid inlet collector of said cylindrical wall include a plurality oftubes extending substantially horizontally transversely of said annularinlet collector means of said cylindrical wall at the bottom of thelatter and each connected at one end thereof to said outlet end of saideconomize-r means, a header communicating with the other ends of saidhorizontal tubes, and a plurality of tubes connecting said header tosaid annular inlet means.

References Cited by the Examiner UNITED STATES PATENTS 2,170,349 8/1939Bailey 122250 FOREIGN PATENTS 1, 194,599 5/1959 France.

874,063 8/1961 Great Britain.

KENNETH W. SPRAGUE, Primary Examiner.

1. A ONCE-THROUGH TYPE BOILER COMPRISING, IN COMBINATION, AN OUTERUPRIGHT SUBSTANTIALLY CYLINDRICAL WALL FORMED BY A PLURALITY OF TUBESEXTENDING SUBSTANTIALLY PARALLEL IN CONTACT WITH EACH OTHER INSUBSTANTIALLY HELICAL FORM FROM THE LOWER TO THE UPPER END OF SAIDCYLINDRICAL WALL AND BEING WELDED TO EACH OTHER; A SUBSTANTIALLYVERTICAL SEPARATING WALL EXTENDING TRANSVERSELY THROUGH THE INTERIOR OFSAID CYLINDRICAL WALL AND BEING FORMED BY A PLURALITY OF SUBSTANTIALLYVERTICAL TUBES WELDED TOGETHER THROUGH A SUBSTANTIAL PORTION OF THELENGTH THEREOF, SAID VERTICAL WALL DIVIDING THE INTERIOR OF SAIDCYLINDRICAL WALL INTO A FURNACE CHAMBER AND A HEAT EXCHANGE CHAMBER,SAID TUBES OF SAID VERTICAL WALL BEING SPACED AT UPPER PORTIONS THEREOFFROM EACH OTHER TO PROVIDE COMMUNICATION BETWEEN SAID FURNACE CHAMBERAND SAID HEAT EXCHANGE CHAMBER AT AN UPPER PORTION OF SAID SEPARATINGWALL; BURNER MEANS COMMUNICATING WITH THE INTERIOR OF SAID FURNACECHAMBER; HEAT EXCHANGE MEANS IN SAID HEAT EXCHANGE CHAMBER; AND TUBULARMEANS CONNECTING THE TUBES OF SAID CYLINDRICAL WALL, THE TUBES OF SAIDSEPARATING WALL AND SAID HEAT EXCHANGE MEANS TO EACH OTHER FOR PASSAGEOF FLUID IN A CONTINUOUS PATH THERETHROUGH.